A generic valve arrangement is known from DE 201 16 920 U1. Valve arrangements of this type are used to activate piston/cylinder arrangements in which, within a cylinder space, a piston is located, to one side face of which is connected one end of a piston rod which is extendable out of the cylinder space and is retractable into this. The space beneath the piston is located on that side of the piston which the piston rod adjoins, whereas the space above the piston is arranged on the other side of the piston. As a result, the cross-sectional area of the space above the piston is greater than the cross-sectional area below the piston, because, in the case of the latter, the cross-sectional area of the piston rod is subtracted. When high-pressure fluid is supplied to the spaces above and below the piston, the piston moves in the direction of the extension of the piston rod; when the space above the piston is relieved in that this space and the fluid located in it are connected to a reservoir which is at low pressure, also called a low-pressure tank, the piston moves in the opposite direction on account of the high pressure in the space below the piston, so that the piston rod is retracted.
By means of this piston/cylinder arrangement, for example, the movable contact pieces of a high-voltage circuit breaker can be actuated.
Of course, by means of such a piston/cylinder arrangement, other components can also be moved, such as, for example, crane arms, buckets or bucket excavators, and the like.
In many applications, for example, a changeover is to take place without reversal losses, that is to say when a volume flow from the pressure connection via the two control edges to the low-pressure tank is to be avoided during the switching operation, so that a different flow resistance or volume flow, depending on the switching position, a short switching time or actuation by means of a low pilot control volume can be achieved.
However, when a 3/2-way valve is used, these specifications often can be fulfilled only inadequately or at a high outlay in production terms and with high production costs. If two 2/2-way valves are used as main control valves, in the event of a changeover the open valve first has to be closed before the closed valve is opened, if a reversal loss is to be avoided and if no further measures are taken. However, for this purpose, in the case of pilot-controlled valves, at least two pilot control valves with suitable activation electrics, for example with time-delayed or sensor-controlled triggering of the second valve, should be used. This entails further high costs and an unnecessarily long delay in the opening of the second 2/2-way valve after the closing of the first.